**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Joshua Bomsztyk
National Amyloidosis Centre
London
UK

**Main Body of the Abstract**
Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) with free light chain specific reagents (FLC-MS) is a novel method for the detection of a monoclonal serum FLC. FLC-MS negativity is associated with improved survival and organ response independent of the haematological response.1 We have further analysed the impact of FLC-MS negativity on survival, time to next treatment (TTNT) and organ response in a cohort who achieved a complete haematological response (CR).
487 patients underwent FLC-MS assessment at baseline and at 12-months post treatment. At the 12-month timepoint 164 (33.7%) patients achieved a CR by ISA criteria and 64 (39%) of these patients were FLC-MS negative. Median overall survival was not reached in either cohort (FLC-MS negative vs. positive) (p=0.071). A cardiac response was seen in 22/32 (68.8%) vs. 35/64 (54.7%) (p=0.269) and a renal response in 17/43 (39.5%) vs 22/62 (35.5%) (p=0.446).
23/64 (35.9%) vs. 48/100 (48%) patients (FLC-MS negative vs. positive) received second line therapy. Median TTNT was 85 vs. 71 months (p=0.027) respectively (Fig 1). 4/64 (6.3%) vs. 14/100 (14%) (p=0.121) required therapy within 24 months. For those with a dFLC <10mg/l at 12 months median TTNT was 84 vs 71 months (p=0.109) and median TNTT was NR vs. 75 months (p=0.096) for patients with an iFLC<20mg/l (FLC-MS negative vs. positive).
Overall patients who achieve FLC-MS negativity plus CR vs. CR alone have an improved survival and TTNT. There is a trend that organ response rates are also superior in FLC-MS negative patients.



Time to next treatment is longer in patients with a haematological complete response who are FLC-MS negative vs. positive PA107 (#76)

We invite you to attend the XIX International Symposium on Amyloidosis to be held in Rochester, MN.

This symposium is organized as a hybrid meeting (with the focus on in-person) held from Sunday, May 26 through Thursday, May 30, 2024.

Together with the ISA Board and members of Mayo Clinic, a very attractive scientific hybrid program is being planned. The program will cover a variety of types of systemic amyloidosis: ATTR (hereditary and wild-type), AL (light-chain), AA and less frequent forms. There will be key lectures, specific symposia including those company sponsored, oral presentations and poster sessions of accepted abstracts.

COURSE DESCRIPTION
This program will provide a comprehensive review of state-of-the-art education in systemic amyloidosis: basic science, pathophysiology, diagnosis, current and emerging treatments. Scientific presentations will include competitive oral and poster abstracts. The rapid evolution of scientific discovery and expanding treatment options has created tremendous interest in the field and this meeting will fill and important gap in educating scientists and clinicians.